Awareness of surgical smoke hazards and enhancement of surgical smoke prevention among the gynecologists.

Surgical smoke is the gaseous by-product produced by heat generating devices in various surgical operations including laser conization and loop electrosurgical procedures that often are performed by gynecologists. Surgical smoke contains chemicals, blood and tissue particles, bacteria, and viruses, which has been shown to exhibit potential risks for surgeons, nurses, anesthesiologists, and technicians in the operation room due to long term exposure of smoke. In this review, we describe the detailed information of the components of surgical smoke. Moreover, we highlight the effects of surgical smoke on carcinogenesis, mutagenesis, and infection in gynecologists. Furthermore, we discussed how to prevent the surgical smoke via using high-filtration masks and smoke evacuation systems as well as legal guidelines for protection measures among the gynecologists.

Introduction

Cervical cancer remains to be one of the leading causes of cancer-related death in women despite advances in screening, diagnosis, prevention, and treatment. An estimated 13,240 patients will be diagnosed with cervical cancer in the United States in 2018 and about 4,170 cases will die because of this deadly disease, corresponding to almost 11 deaths per day 1. Therefore, to obtain the better treatment outcomes, the prevention is imperative via early detection of precancerous and high-grade cervical intraepithelial neoplasia (known as cervical dysplasia, CINII and CINIII), which is the potentially premalignant transformation and abnormal growth (dysplasia) of squamous cells on the surface of the cervix 2-4. Emerging evidence has demonstrated that virus infection and multiple molecular signaling pathways were critically involved in cervical tumorigenesis. Studies have revealed that human papillomavirus (HPV) infection is associated with progression of CINII and CINIII, and invasive cancer. Especially, patients with infection of HPV strains 16 and 18 cause about 70% of CINII, CINIII, and cervical cancer 3, 5, 6. Thus, HPV vaccine is useful for prevention of the cervical cancer.

The treatment of CIN is effective and safe 7, 8. The cervix lesions need to be treated with an ablative approach or an excisional technique, which are dependent on the size and location of the lesion 9. The ablative approaches have cryotherapy and thermal ablation, while excisional methods have large loop excision or cold knife conization. Currently, the treatment for CIN applies for laser and electrosurgical managements. Laser conization and electrosurgical procedures such as the loop electrosurgical excisional procedure (LEEP) have been considered as accurate techniques in cervical cancer prevention 9-11.

To date, using electrocautery and lasers by gynecologists in cervical cancer and ovarian cancer is frequent, especially LEEP treated for CINII and CINIII with HPV infection, which may cause a critical healthy problem due to gaseous byproducts or “surgical smoke'' produced by these devices. Surgical smoke poses a wealth of potential risks to the gynecologists, including the direct physical injury, mutagenicity and transmission of infectious diseases especially HPV. However, legal guidelines and standardized recommendations within the gynecologists have not yet been established. Thus, in the following sections, we will review the contents and potential risks of surgical smoke and offer some recommendations for gynecologists to minimize the hazards.

What is the surgical smoke?

Surgical smoke is the gaseous by-product produced when tissue is dissected or cauterized by heat generating devices such as lasers, electrosurgical units, ultrasonic devices, and high speed burrs, drills and saws. Among these devices, the most common sources are electrocautery ablation and laser ablation 12, 13. During the surgical procedures, the heat of a diathermy causes the target cell membranes to rupture to its boiling point, and subsequently generates a plume of smoke containing mostly water vapor and then releases into the atmosphere of the operating room 13, 14. At the same time, the intense heat created by chars protein and other organic matter within the cells causes thermal necrosis in the adjacent cells. The charring of cells also releases other harmful contaminants, such as carbonized cell fragments and gaseous hydrocarbons 15.

Surgical smoke, the encompassing term for a number of gaseous byproducts produced by energy-based surgical instruments, is also known as plume, aerosols, smoke, cautery smoke, diathermy plume and smoke plume 14, 16-18. Most of these terms are often used interchangeably. However, the term “smoke”, although it is not formally correct in all cases, is used to describe this surgically generated gaseous by-product 18.

The risks of surgical smoke

There are many disadvantages of surgical smoke, such as hindering the vision of the surgeon, producing an unpleasant odor, and releasing hazardous chemicals that include mutagens and carcinogens into the environment of operating room 19, 20. A current study that was carried out in the operating rooms with 45 nurses and 36 doctors demonstrated that all of the 81 nurses and doctors exposed to surgical smoke experienced headaches, watery eyes, coughs, burning throats, nausea, bad odors absorbed in the hair, drowsiness, dizziness, sneezing and rhinitis 21. In addition to the harmful chemicals, surgical smoke has been demonstrated to harbor contagious, viable malignant cells, and even to contain live bacteria and viruses, including HPV and human immunodeficiency virus 22-24, all of which may induce great damage to the persons in the operation rooms. For example, 80% smoke plumes were found to be positive for HPV from patients with HPV-positive CIN after LEEP treatment, suggesting that stringent control procedures could be required to protect gynecologist 23. Each year, in America, a total of approximately 500,000 personnel including surgeons, nurses, anesthesiologists, and technicians were exposed to surgical smoke in the operating rooms, and these exposures were cumulative over their lifetimes 25. Even though surgical smoke is not an immediate health hazard, operating room personnel should be aware of the potential long-term health risks.

The components of surgical smoke

Chemical compositions and hazards

Surgical smoke is made up of 95% water or steam and 5% cellular debris in the form of particulate material which is composed of chemicals, blood and tissue particles, viruses, and bacteria 17, 26. As the studies revealed, the size of the particulate matter is decided by the device used and tissue type 26. Electrocautery creates particles with the smallest mean aerodynamic size (0.07μm), whereas laser tissue ablation creates larger particles (0.31μm) 27, 28. On the other hand, Karjalainen et al. 29 compared the deposition of particulate matter in ten different tissues containing skeletal muscle, liver, lung, bronchus, subcutaneous fat, renal pelvis, renal cortex, cerebral gray and white matter, and skin, all taken from the porcine tissues. The results showed that liver produced the highest number of particles, skeletal muscle and renal tissues produced a medium mass of particulate matter, while other tissues produced significantly less particulate mass, firmly suggesting the obvious differences in particle production of the surgical smoke depending on the electrocauterized tissue types 29.

There are mounting evidences suggesting that particles about 5 μm or larger are deposited on the walls of the nose, pharynx, trachea, and bronchus, while those smaller than 2 micrometers are deposited in the bronchioles and alveoli 26-28. Besides, 77% of particles inside the plume are less than 1.1μm with a mean diameter of 0.07μm 30, 31, and a mean diameter of 0.22 μm to 0.056 μm are certainly in the inspirable range 17. Therefore, smoke may induce acute and chronic inflammatory changes, including alveolar congestion, interstitial pneumonia, bronchiolitis, and emphysematous changes in the respiratory tract 18, 28. Baggish et al. 32, 33 reported that laser-produced surgical smoke was harmful to the lungs of rat models. In the study, it was observed that the inhalation of surgical smoke caused amount of damage from inflammatory interstitial pneumonia to extensive emphysema and that the changes proportionally increased with extended exposure. Moreover, Gates et al. 34 also reported that long-term exposure to surgical smoke, as measured by the duration of operating room employment, appears to increase the risk of chronic pulmonary conditions other than lung cancer, such as asthma or pneumonia. Another survey by Ball et al. 35 found that, compared to the general population, perioperative nurses displayed twice the incidence of some respiratory problems such as sinus problems, infections and bronchitis. Although the study did not discover any correlation between the inhalation of surgical smoke and respiratory problems, these findings could be a wake-up call for concern, as these conditions have been linked to inhaling surgical smoke.

In vitro investigation has identified many chemicals in the surgical smoke plume 12. So far, researchers have identified more than 80 chemical compounds in the surgical smoke 36. The most abundant chemicals in electrocautery smoke are hydrocarbons, nitriles, fatty acids and phenols. The plumes generated by laser tissue ablation include benzene, formaldehyde, acrolein and polycyclic aromatic hydrocarbons 28. In addition, surgical smoke from adipose tissue produces more aldehydes than ketones whereas epidermal tissue ablation creates more toluene, ethyl benzene, and xylene 37. Similar to this concept, another elegant study identified 9 main carcinogenic chemical compounds in surgical smoke form porcine tissues, butadiene, benzene and furfural was demonstrated to be obviously exceeded permissible exposure 38. Further analyses revealed that as compared to muscle tissue, liver tissue of porcine contributed to higher concentrations of butadiene, benzene and furfural when cauterized in electrosurgery 38. Chung et al. 20 collected 12 smoke samples from a continuous irrigation suction drainage system during TURP (transurethral resection of the prostate) and vaporization. This study showed that there were 16 main chemical constituents of surgical smoke including propylene, allene, isobutylene, 1,3-butadiene, vinyl acetylene, mecaptomethane, ethyl acetylene, diacetylene, 1-pentene, ethyl alcohol, piperylene, propenylacetylene, 1,4-pentadiene, cyclopentadiene, acrylonitrile and butyrolactone. Moreover, a recent study conducted by Sisler et al. 39 collected 36 surgical smoke samples by using an electrocautery surgical device to cut human breast tissues and characterized the particles from plumes. They detected 17 different volatile organic compounds in all the 36 surgical smoke samples, and high concentrations of acetaldehyde, ethanol and isopropyl alcohol were detected in every sample predominantly.

Acrylonitrile, is a colorless and volatile chemical that is able to be absorbed through the skin and lungs and exerts its toxicity by liberating cyanide 27. The exposure levels of operating room personnel to acrylonitrile have been demonstrated to be 1.0-1.6 parts per million (ppm) 40. Short-term exposure to acrylonitrile can cause eye irritation, nausea, vomiting, headache, sneezing, weakness and lightheadedness, whereas long-term exposure causes cancers in laboratory animals and has linked to higher incidences of cancer in humans. Repeated or prolonged exposure of the skin to acrylonitrile may produce irritation and dermatitis 28.

Hydrogen cyanide, which is liberated by acrylonitrile, is also a toxic colorless gas that can be absorbed into the lungs through the skin and the gastrointestinal tract 17. Excessive exposure to hydrogen cyanide can cause cardiac arrhythmias, dyspnea, coma and even death, while chronic low level exposure may result in neurological effects such us headache, vertigo, nausea, and vomiting 15, 27. Therefore, the United States Department of Health and Human Services has set the short-term exposure limit of hydrogen cyanide at 10 ppm 40.

Benzene has been detected at high levels (71 μg/m3) near the electrocautery pencil during colorectal surgery and in the ambient air of the operating room (0.5-7.4 mg/m3) 39. In epidemiological study, clinical and laboratory data linked benzene exposure to aplastic anemia, acute leukemia, and bone marrow abnormalities 25-27, 42. As stated by Occupational and Safety Health Administration (OSHA) 26, the short-term effects of benzene include headache, dizziness, nausea, and irritation of the eyes, nose, and respiratory tracts. National Institute of Occupational Safety and Health (NIOSH) recommended that exposure limit of benzene is 0.1 mg/m3 and the OSHA limit of benzene is 0.2 mg/m3.

Carcinogens in surgical smoke

Among these chemical compounds existing in surgical plume, acetaldehyde, acrolein, acrylonitrile, benzene, cyclohexanone, formaldehyde, furfural, polyaromatic hydrocarbons, styrene, toluene and xylene have been classified as carcinogens by the IARC (International Agency for Research on Cancer) 43. 1,3-butadiene, vinyl acetylene and acrylonitrile have been demonstrated to be very toxic and carcinogenic further 20. One study by Oganesyan et al. 44 used a well-established method to collect the smoke during active electrosurgery placed at 16 to 18 inches above the cautery point. The results showed the high concentrations of known carcinogens in surgical smoke such as benzene, butadiene, and acetonitrile. In addition, butadiene and benzene showed 17- and 10-fold higher concentration than second-hand smoking, respectively, which have been reported to cause acute or delayed toxicity and have potential carcinogenic effects on humans.

Laboratory and animal studies have demonstrated that smoke generated during laser and electrocautery surgery causes acute or delayed carcinogenic effects on humans. Even though there is no direct evidence to show that surgical smoke is carcinogenic to humans, there are persistent concerns.

Mutagenic potential of surgical smoke

As well as chemical components, the mutagenicity and cytotoxicity were of greatest concern to users of lasers, electrosurgery, and powered surgical instruments. Tomita and colleagues collected the electrosurgery smoke particles generated from mucous membrane of the canine tongue irradiated with a CO2 laser, and found that condensates of surgical smoke have mutagenicity on TA98 in the presence of S9 mix, and His+ revertants were induced with an increased dose of the condensates 45. This result demonstrated the mutagenicity of a TA98 strain of Salmonella. Moreover, the authors quantified the mutagenic effect created by thermal destruction of 1 g of tissue was equivalent to that of three to six cigarettes respectively. Then, Gatti et al. 46 used the standard Salmonella microsomal test, an established technique for evaluating the mutagenicity of a substance, to assess the mutagenic potential of the electrocautery-derived smoke created during the reduction mammoplazy, and found the mutagenicity of smoke to a TA98 strain of Salmonella. In a subsequent laboratory study with porcine liver tissue repeatedly cutting by electro-surgical hook knife, authors collected the plumes and observed that the clonogenicity of the MCF-7 human breast carcinoma cells decreased about 30% when exposed to this plumes, suggesting the cytotoxicity of electro-surgical smoke 47, 48. Additionally, an in vitro experiment has discovered that surgical smoke from human breast tissues via electrocautery surgical device induced cytotoxicity in human small airway epithelial cells and mouse macrophages 39, implying that surgical smoke may be an occupational hazard to healthcare workers. It was not determined in either study whether the plumes actually posed a serious health risk to perioperative personnel, but more attention should be paid for surgeon to safe levels of ambient mutagens.

Biological components of surgical smoke

Viable malignant cells

In addition to the various chemical compositions, surgical smoke also contains transmissible, viable malignant cells. As early as 1999, Fletcher et al. 24 cauterized pellets of B16-F0 mouse melanoma cells to collect plums and assessed cell viability by the way of the trypan blue assay and the tetrazolium viability assay, which showed that viable melanoma cells were present in the culture wells. These results demonstrated that plumes of electrocautery contained malignant cells which was viable and may explain the appearance of port-site metastases that were remoted from the surgical dissection or never in direct contact with the tumor. Another study also assessed the ability of surgical smoke to spread aerosolize malignant cells by the way of collecting thirty-five patients undergoing elective laparoscopy. As a result, aerosolized mesothelial cells were identified only in two patients, but one patient who displayed cellular aerosolization developed a port-site recurrence after following-up 2 to 7 months 49. In the same year, other researchers collected surgical plume with Transwell membrane from various tumour cell lines (NCI-H292, FaDu, KB, AGS, ARO) cauterized by electrocautery, radiofrequency ablation and ultrasonic scalpels. These experiments demonstrated that it was only from the ultrasonic scalpel, but not from the electrosurgical unit or radiofrequency ablation device that viable cells were identified in all 25 smoke samples retrieved from a distance of 5 cm 50. However, no more study has demonstrated the transmission of cancer cells to operation room personnel during electrosurgery 31.

Viable bacteria

A study by Schultz et al. 51 has demonstrated the extent of viable bacteria present in surgical plume with an experimental model of porcine tissue embedded with Serratia marcescens, which transmitted directly to operation room personnel. The researchers concluded that it was the blended current electrosurgery rather than pure coagulation electrosurgery that transmitted bacteria to nearby or adjacent sites.

Virus and its infection in gynecologist

HPV was detected in surgical smoke

The first insights into the infection of surgical smoke were those numerous animal and human studies about the viruses in the smoke to date. Several articles stated that HPV was not found in the plume, and others demonstrated that the risk of HPV contamination was low or impossible for the operation room staff 52, 53. Weyandt at el. 52 collected petri dishes placed in 1 and 2 m distance to the treatment weld and swabs from the glasses and nasolabial folds of the operating physician to assess the generation of aerosols containing HPV DNA during treatment of genital warts with multilayer argon plasma coagulation and with CO2 laser ablation. They confirmed that HPV types of genital warts were not found in any of the petri dishes and swabs obtained during this treatment. Despite of the ability to transmit HPV DNA in surgical plume, the risk of dispersal of HPV to surgeons and the development of clinically active infection appears to be low 53.

However, the risk of occupational human papillomavirus transmission from patient to medical personnel during laser vaporization procedures remains controversial. As early as 1988, in order to analyze the viral DNA content in the vapor produced by the carbon dioxide laser during the vaporization of papillomavirus-infected verrucae, Garden et al. 54 used two models for evaluation: an in vitro cutaneous bovine fibropapilloma and an in vivo human plantar or mosaic verruca model, both of which demonstrated that intact viral DNA was in the plume collected during carbon dioxide laser therapy of papilloma virus-infected verrucae. Next year, Sawchuk et al. 55 also used a bioassay to demonstrate the presence of human papillomavirus DNA in surgical smoke derived from human plantar warts treated with carbon dioxide laser and electrocoagulation. In a subsequent study, Garden and colleagues went on to collect the laser plume from bovine papillomavirus-induced cutaneous fibropapillomas and then reinoculated onto the skin of calves. The results revealed that substantial amounts of bovine papillomavirus DNA were present in all of the laser plume samples and tumors developed in all of 3 calves in sites of control bovine papillomavirus (BPV) concentrate inoculums were infected with the same virus type, confirming that bovine papillomavirus isolated from carbon dioxide laser plume did induce lesions in healthy animals 56. Later, many studies have demonstrated the presence of HPV in the plume. Sood et al. 23 conducted a study of 49 patients with evidence of CIN undergoing loop electrosurgical excision procedures. In the study, 39 plume samples were reported to be positive for HPV, with 16/18 most, which showed that the plume of smoke generated by LEEP had HPV DNA. Furthermore, according to a study including patient tissue samples from the urethral warts (n = 5), laryngeal papilloma (n = 5) which were all found positive for HPV, and the surgical gloves (n = 20) used by the employees such as the physicians and nurses. The results showed that all samples obtained from the surgical gloves tested positive for HPV after urethral warts procedures, and in one of the five surgeons and in three of the five nurse tested HPV positive after the treatment of laryngeal papilloma, respectively. Interestingly, all HPV genotypes presented were identical to the HPV of corresponding patient tissue specimens 57. A relatively recent study evaluated HPV subtypes between the resected cones of LEEPs and the surgical plume resulting from LEEPs of high-grade squamous intraepithelial lesion of the cervix uteri and surprisingly found that these plumes contained high-risk HPV which was consistent with HPV subtypes identified in the resected cones. The further investigations of contamination with surgical plume are necessary for evaluation of potential hazards to be involved in gynecologists 58.

The infection of HPV found in gynecologist due to surgical smoke

Although the possibility of disease transmission through surgical smoke exists in humans, actual documented cases of pathogen transmission are rare. Four cases have essentially been proven. A 44-year-old gynecological laser surgeon, who had no respiratory diseases and was healthy, developed laryngeal papillomatosis and infected with HPV types 6 and 11 after treating patients with anogenital condylomata known to harbor the same viral types 59. In Germany, a 28-year-old gynecological operating room nurse, who assisted repeatedly in electrosurgical and laser surgery in excisions of anogenital condylomas, developed a recurrent and histologically proven laryngeal papillomatosis. The expert opinion of a virological institute confirmed a high probability of correlation between the occupational exposure and the laryngeal papillomatosis 60. A 53-year-old male gynecologist who have performed laser ablations and LEEP on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice, presented with HPV 16 positive tonsillar squamous cell carcinoma. However, he had no identifiable risk factors other than long term occupational exposure to laser plumes. Another patient was a 62-year-old male gynecologist with a 30 year history of laser ablation and LEEP, having very few other risk factors for oropharyngeal cancer or HPV infection, subsequently developed HPV 16 positive base of tongue cancer 61. Due to that HPV could induce inflammation and carcinoma, protective measures should be instituted for all healthcare personnel, particularly gynecological surgeons 62.

Other virus in surgical smoke

In addition to HPV, human immunodeficiency virus (HIV) is also receiving a lot of attention because of its increasingly prevalence in the general population. Baggish et al. 22 conducted a research in which HIV proviral DNA was captured in the inner lumen of smoke evacuation tubing after in vitro laser vaporization of cultured HIV cells. This study has clearly shown that HIV was present in the laser smoke. Furthermore, Taravella et al. 63 found that infectious polio virus could be propagated in the plume collected from oral polio virus infected fibroblasts by means of an excimer laser. The evidence of a recent study revealed that hepatitis B virus (HBV) was present in surgical smoke. Kwak et al. 64 collected surgical smoke from 11 patients undergoing laparoscopic or robotic surgery. In sequence of HBV gene amplification and DNA sequencing, the authors found that HBV was detected in 10 of the 11 samples of surgical smoke.

Protective measures for gynecologist

Mask: an effective protector

After completing a search of the literature, all articles in this literature synthesis identified personal respiratory protection to prevent surgical smoke inhalation injury, such as a basic surgical mask, high-filtration mask, or an N95 respirator 65. Surgical masks, in general, providing more than 90% protection for the patient and the operating room staff from exposure to surgical smoke, have been in use for more than a century 66. Today, the focus of protection has shifted to how surgical masks can be used as a safeguard for the surgical staff from surgical smoke.

In one report of Sawchuk et al. 55, the authors conducted repeat experiments analyzed by dot-blot hybridization to identify whether placing a surgical mask in the vapor path could inhibit the papillomavirus in surgical plume. The results showed that no viral DNA was detected from vapor after placing a mask and abundant viral DNA was extracted in this mask, which strongly suggested that the potential risk of surgical smoke inhalation might be markedly reduced by wearing a surgical mask. Lewin et al. 26 also suggested that high-filtration masks should be used to prevent exposure in surgical smoke. However, the conclusion of the research by Oberg et al. 67 indicated that none of these surgical masks exhibited adequate filter performance can be considered respiratory protection devices. In this research, filtration performance was evaluated by means of monodisperse latex sphere and sodium chloride aerosols, and facial fit of surgical smoke was evaluated by qualitative and quantitative fit tests. As a result, all 9 masks exhibited a wide range of particle penetration both in latex sphere challenge tests (0%-84%) and sodium chloride challenge tests (4%-90%), respectively. Another assay described that live, infectious virus was extracted from the plumes behind all surgical masks tested, suggesting that influenza virus surviving in aerosol particles could be able to bypass or penetrate a surgical mask 68. Besides, to be effective, respirator filtering materials must allow only minimal penetration of the contaminant and provide an airtight faceseal or positive pressure inside the facepiece. However, traditional surgical masks fulfill neither of these requirements. Their vulnerability of penetration demonstrated that surgical masks offered only partial protection because they filtered out particulates only as small as 5μm in diameter, by the way when sizes smaller than 5 μm, these particles were not filtered by surgical masks and might be inhaled by personnel in the operation room 31. In addition, even high-filtration masks also referred to as laser masks, whose filter particles are about 0.1 micrometers in size 65, 69. Actually, the particulate size of the particles in the smoke has been documented to be much smaller than 5μm particulate diameter that standard surgical masks could filter 17. Bacteria can be as large as 30μm or smaller as 0.3 μm, and viruses are smaller and can range in size from 0.01μm to 0.3 μm. Besides, it has been reported that small particles less than 1.1 μm in diameter constitute 77% of the particulate matter found in surgical plume 69. As a result, most surgical masks do not have adequate filtering or fitting attributes to provide respiratory protection for wearers.

Some current-model surgical masks such as Health Care Particulate Respirators categorized into N, R and P classes have greater filtering and face seal capabilities, and the most commonly used are N95 and other NIOSH-approved respirators 70. Emerging evidence has illustrated the high efficiency particulate air (HEPA) filters are capable to arrest fine particles effectively, such as N95 respirator masks 71, which have the filter efficiency over 95% when challenged with 0.3 μm aerosols. Although no guidelines on the use of respirators for surgical procedures, it seems that respirators that are at least N95 grade provide the best protection against surgical smoke produced during the use of electrocautery, lasers, or ultrasonic scalpels. In the study of Edwards et al. 72, suggested that the key respiratory protection was the use of N95 and other NIOSH-approved respirators, because it was the only respiratory protection choice proven effective for personnel protection. Another research by Gao et al. 73 calculated the total protection factor to measure the performance of common surgical masks, N95 and N100 which were exposed to the surgical smoke collected from surgical dissections on animal tissue by standard electro-cautery device. The results of this study revealed that the total protection factor of common surgical masks was close to 1 which provided minimal protection against surgical smoke, while the total protection factor of N95 surgical mask respirator was 208-263 and N100 filtering face piece respirator was 1,089-2,199, which could offer a higher level of protection. Notably, an elegant study compared the filtration efficiency of airborne bacteria between N95 respirator and disposable surgical mask, as a result, the filtration efficiency of N95 and disposable surgical mask were 99.93% and 91.53%, respectively, demonstrating the significant difference between the two masks 74. Consistent with these findings were data showing that N95 respirators provided more protection in case of clinical respiratory illness and laboratory-confirmed bacterial, suggesting the effective use of respiratory protection for healthcare workers 75.

On the contrary, some researchers found that it was very difficult to breathe with an N95 mask because CO2 levels elevated significantly, and it was easy to have some subjective symptoms, the complaints of headache, lightheadedness, and difficulty in communication 76. Compared to nurses with lower body mass indexes, nurses with a higher body mass indexes had even more negative effects on some physiologic measures such as lower O2 levels and higher heart rate, and worse subjective symptoms such as higher perceived exertion, shortness of breath, thermal discomfort, headaches, lightheadedness, and visual challenges 76.

Other useful measures for gynecologist

It is clear that masks especially N95 are important but not sufficient. Nowadays, protection measure with activated carbon fiber is increasingly acknowledged 71. The combination of HEPA filters with activated carbon is commonly called “high efficiency gas adsorption” (HEGA) filters, which successfully prevent surgeons from volatile organic compounds and chemical vapors in surgical smoke 77. The mask contains an activated carbon layer may provide the surgeon with additional protection 78. Remarkably, a recent study has demonstrated that the risk of surgical smoke exposure during laparoscopic surgery could be reduced by activated carbon fiber filters 79. Eighteen chemical components were discovered in the sample collected 20 min after the electrocautery device used. However, When using the activated carbon fiber filter, known carcinogens including 1,2-dichloroethane, benzene, and ethylbenzene were dramatically reduced by more than 85% and the risk was extremely eliminated, implying that operating room personnel should pay attention to the risk from surgical smoke and minimize this risk by using activated carbon fiber filter 79. However, these activated carbon fibers have not been demonstrated in clinical practice, which deserve further investigation before a formal recommendation in gynecology and other surgeons.

In addition, another important precaution is proper and diligent use of a smoke evacuation system with a high efficiency filter. Smoke evacuation has been identified as a feasible and potentially useful way to reduce the surgical smoke 80. Smoke evacuation is able to capture the smoke generated at the surgical site and remove it to an area away from the surgical team where it can be filtered, which have been shown to be the most effective in limiting exposure to the noxious odor and potential health hazards of electrosurgical and laser plume 81, 82. The unanimous consensus of all such recognized authorities that the primary measures for protecting people against surgical smoke are local exhaust ventilators, which is composed of wall suction with an in-line particulate filter and smoke evacuator. It filters 99.9995% of contaminants ranging 0.12 microns or larger in diameter 81. Consistently, one experiment tested the efficiency of portable smoke evacuation systems and found these filtration reduced surgical smoke up to 99%, however, this accompanied by high sound level, which exceeded recommended threshold limits 83. Controversially, accumulated evidence has demonstrated the poor efficiency for smoke evacuation system in eliminating volatile organic compounds. One experimental study found that some chemical compounds such as acetaldehyde, acetone, acetonitrile, benzene, hexane, styrene and toluene could be detected but at lower concentrations less than the recommended exposure limits when local exhaust ventilation system is in place 84. Besides, another group illustrated smoke evacuation system was unable to reduce some chemical compounds containing butadiene and benzene below the permissible exposure limits 38. Despite recommendations from various professional organizations advocating the use of local exhaust ventilators and respiratory precautions, these measures are not being widely used because of its noise, cost, lack of equipment or repair parts, physician resistance, staff complacency, large and unwieldy local exhaust ventilators devices, and extra personal accommodating devices 72, 76, 85. A recent web-based survey by Steege et al. 85 examined current surgical smoke practices of local exhaust ventilators and personal protective equipment which include respiratory protection approved by NIOSH. There were 4533 respondents to the survey, 56% were nurses and 21% were anesthesiologists, the rest were technologists and surgical assistants. The researchers found that only 14% of respondents reported that local exhaust ventilators were always used during the procedures of electrosurgery, and fewer than half (47%) of the facilities used by survey respondents for most laser procedures. Of particular interest to gynecologists, 49% and 44% of survey respondents reported that they never had training on the hazards of surgical smoke in laser surgery and electro-surgery, respectively. Many studies demonstrated that better or more adherence of education was needed to raise awareness of potential hazards in surgical smoke and to awaken consciousness of a clear lack of health care personal protective measures, which might be served as a foundation to help inform safety guidelines in electrosurgery for formal gynecologist and obstetrician residents 86, 87. A team of perioperative nurses and surgeons quantified smoke-evacuator use, assessed staff members' knowledge and presented a multimodal education program in order to improve compliance with policies and procedures for surgical smoke management in the operation room. As a result of a posteducation, this survey showed a 14.6% increase in surgical smoke-evacuation use which obviously revealed significant improvement in staff members' awareness about reducing surgical smoke in the operation room and helping patients, staff members, and the surgical team to ensure a safe environment 88.

Additionally, disposable smoke evacuation hose is one of the most previous ways used in electrosurgery to reduce surgical smoke 89. Elimination of surgical smoke via a disposable built-in-filter trocar has been identified as a simple and effective way to reduce chemical compounds such as benzene, toluene, butyraldehyde, ethylbenzene, xylene, styrene, formaldehyde, and propionaldehyde, to some extent 90.

Besides, general room ventilation using a central plume evacuation system connected to several operating suites was also insufficient to effectively capture smoke generated at the surgical site 91. These central evacuation systems removed the smoke directly to a remote site without using filters, and the captured device connected through tubing to a control panel that controlled the flow rate 81.

In spite of these protections, the existing problems on protections are obvious. On one hand, the outpatient department where most gynecological procedures of treating CIN are performed and operation room have a paucity of protective structures to protect gynecologists, our staff and our patients, there being neither any smoke evacuation system, filter, wall suction, nor a protocol regarding protection against surgical smoke 21. On the other hand, most surgeons, perioperative personnel, and health care organizations lack a general knowledge regarding the potential health risks associated with exposure to surgical smoke and underuse of equipments that may provide effective protection because of inconvenience and expense 76, 87, 92. Many surveys revealed that effective engineering controls, such as local exhaust ventilation procedures, were used by fewer than half of the facilities represented by survey respondents for most laser procedures and in very few facilities for most electrosurgery, electrocautery, or diathermy procedures 17, 65. However, the organisations responsible for protecting the health of the workers in different countries have still not issued formal guidelines for the treatment and removal of the surgical smoke generated in both open and laparoscopic procedures. As gynecologists, we must realize that our decision of rejecting protective measures against surgical smoke will inevitably put not only ourselves but also our staff at risk. Therefore, what we also need is further training and reinforcement of universal precautions to reduce occupational exposures.

Conclusion and perspective

It is obvious that surgical smoke is dangerous to gynecologists who perform procedures using electrocautery and other heating process to treat CIN. Electrocautery creating particles are small enough to be inhaled through a surgical mask and deposited on the walls bronchioles and alveoli causing pulmonary diseases (List in Figure 1). Several particles contain chemical compounds known as carcinogens and biological substances considered mutagenic and possibly infectious, including malignant cells and viruses (List in Table 1). Further research should be encouraged to quantify the exposure of gynecologists to surgical smoke in the outpatient department. A number of areas not only require more investigation and research to demonstrate the harmful effects of surgical smoke and analyze the contents of the smoke, but also need long-term studies on exposure limits. In spite of doubting about the harmful effects of exposure to surgical smoke, caution should be applied and preventive measures within should be carried. Many guidelines indicate that the most important protective measure against surgical smoke is consistent and correct use of smoke evacuation and surgical mask. But these measures are not consistently implemented, nor are they legally mandated. Therefore, firstly, the diligent use of high-filtration masks in addition to smoke evacuation systems to gynecologists performing surgery is required. Secondly, increased knowledge and training of the individual to enhance awareness of health care workers about the hazards of the surgical smoke is recommended. Thirdly, it should have positive perceptions about the attributes of smoke evacuation recommendations and ease of understanding and implementing smoke evacuation system. Lastly, these measures should be consistently implemented and legally mandated soon. Altogether, gynecologists should recognize the danger of surgical plume and request all necessary measures to protect both operating room staff and patients.

Figure 1

The hazards of surgical smoke produced by electrosurgical procedures to gynecologists. Surgical smoke produced by electrocautery contained particles small enough to be inhaled and deposited on the respiratory tract causing pulmonary diseases. Surgical smoke also poses chemical and biological components causing potential risks for healthcare workers.

Table 1

The various components of surgical smoke produced by electrosurgical procedures

Year	Surgery type or tissues	Energy device	Components	Ref.
Chemical components of surgical smoke
1998	porcine liver	High-frequency electrocoagulation	2,3-dihydro indene, 3-butenenitrile, pyrrole, 2-nethyl propanol, 2-methyl furan2,5-dimethyl furan, 1 decene, benzonitrile, 6-methyl indole 3-methyl butenal, Methyl pyrazine, 1 undecene,ethynyl benzene, 2-propylene nitrile, indole, furfural, hexadecanoic acid, ethyl benzene, toluene, benzaldehyde, 4-methyl phenol	93
2007	Verrucae, pilonidal sinuses, abdominal procedures	diathermy	nalkanes, n-alkenes and aldehydes as well as toluene, ethyl benzeneand xylene	37
2007	abdominal surgery	unipolar diathermy	hydrogen cyanide, acetylene, and 1,3-butadiene	94
2010	transurethral resection of the prostate	electrosurgical generator	propylene, allene, isobutylene, 1,3-butadiene, vinyl acetylene, mecaptomethane, ethyl acetylene, diacetylene, 1-pentene, ethyl alcohol, piperylene, propenylacetylene, 1,4-pentadiene, cyclopentadiene, acrylonitrile and butyrolactone	20
2012	laparoscopic intraabdominal surgery	Electrocautery or ultrasonic scalpels	benzene, ethylbenzene, styrene, toluene, heptene, and methylpropene	13
2014	laparoscopic cholecystectomy	electrosurgery	benzene, toluene, xylene, dioxins	42
2014	Dermatologic surgery	Monoterminal electrodessication and electrofulguration	1,3 butadiene, benzene, styrene, propylene, acetonitrile, vinyl acetate, n-heptane, 1,2-dichloroethane, chloromethane, hexanone, vinyl chloride	44
2016	laparoscopic or robotic surgery	electrosurgery	HBV	64
2016	Porcine gastric mucosal ablation	electrosurgical probe	toluene, 2-propyl-1-pentanol, perfluorooctan, propenoic acid, dimetyldodecane, 2-ethyl-1-hexanol, propylene glycol	80
2017	rectal cancer resection	electrocauteryand ultrasonically activating scalpel	benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde	90
2018	human breast tissues	Electrocautery surgical device	acetaldehyde,α-pinene, benzene, chloroform, d-Limonene, ethanol, ethylbenzene, isopropyl alcohol, m,p-xylene, methyl, methylene, chloride, n-hexane, o-xylene, styrene, toluene	39
2018	porcine tissue	electrosurgery	acetylene, hydrogen cyanide, 1,3-butadiene,benzene,toluene, furfural, styrene, ethyl benzene and 1-decene	38
2018	porcine tissue	electrosurgery	produce different mass concentration and size distribution of smoke particles.	29
2018	transperitoneal laparoscopic nephrectomy	electrocautery device	ethanol, 1,2-dichloroethane, benzene, ethylbenzene, andstyrene, acetone, 2-butanone, hexane, n-heptane, toluene,p-xylene, n-nonane, o-xylene, n-decane, n-undecane,n-hexadecane, n-tridecane, and n-tetradecane.	79
Mutagenicity and cytotoxicity of surgical smoke
1981	mucous membrane of canine tongue	carbon dioxide laser	mutagenicity of a TA98 strain of Salmonella	45
1992	reduction mammoplazy	electrocautery	mutagenicity of smoke to a TA98 strain of Salmonella	46
1998	porcine liver tissue	electro-surgical hook knife	cytotoxicity	47
2018	human breast tissues	Electrocautery surgical device	cytotoxicity	39
Viable malignant cells in surgical smoke
1999	mouse melanoma cells	electrocautery	viable melanoma cells	24
2009	mouse melanoma cells.	electrosurgery	viable melanoma cells	70
2015	various tumour cell lines	electrocautery, radiofrequency ablation and ultrasonic scalpels	viable cells	50
Viable bacteria in surgical smoke
2015	porcine tissue	electrosurgery	viable bacteria	51
Virus in surgical smoke
1988	papilloma virus-infected verrucae	carbon dioxide laser	intact viral HPV DNA	54
1989	human plantar warts	carbon dioxide laser and electrocoagulation	HPV DNA	55
1991	cultured HIV cells	carbon dioxide laser	HIV proviral DNA	22
1994	CIN	LEEP	HPV DNA	23
1999	oral polio virus infected fibroblasts	excimer laser	infectious polio virus	63
2002	bovine papillomavirus-induced cutaneous fibropapillomas	carbon dioxide laser	bovine papillomavirus DNA	56
2011	genital warts	carbon dioxide laser	HPV DNA	52
2012	urethral warts, laryngeal papilloma	carbon dioxide laser	HPV positive	57
2016	laparoscopic or robotic surgery	electrosurgery	HBV	64
2018	cervix uteri	LEEP	high-risk HPV	58